WO2015107957A1 - Molding material produced using ethylene-(vinyl ester)-type copolymer saponification product - Google Patents

Abstract

Provided is a molten molding material which is produced using an ethylene-(vinyl ester)-type copolymer saponification product (an EVOH resin) and has excellent feed properties during melt extrusion molding. A molding material comprising groups of EVOH resin pellets, said molding material being characterized in that the groups of pellets comprise first EVOH resin pellets each having an approximately circular cross section or an oval cross section and second columnar EVOH resin pellets, wherein the mixing ratio (A1/A2) of the first EVOH resin pellets (A1) to the second EVOH resin pellets (A2) is 99/1 to 20/80 by weight.

Description

Molding material using saponified ethylene-vinyl ester copolymer

TECHNICAL FIELD The present invention relates to a molding material comprising a saponified ethylene-vinyl ester copolymer (hereinafter referred to as “EVOH resin”) pellet group, and more specifically, an EVOH resin pellet group having excellent feedability during melt extrusion molding. It relates to a molding material.

EVOH resin has high crystallinity due to hydrogen bonding between hydroxyl groups present in the polymer side chain, and also has high intermolecular force even in an amorphous part. Based on such a structure, a film using EVOH resin exhibits excellent gas barrier properties.

EVOH resin is molded into a film or sheet such as food packaging material, pharmaceutical packaging material, industrial chemical packaging material, agricultural chemical packaging material, or a container such as a bottle or the like because of its excellent gas barrier property. EVOH resins used as such molding materials are generally distributed as pellets having a length of about 1 to 10 mm.

EVOH resin pellets are generally manufactured by a method called a strand cut method. For example, as disclosed in Japanese Patent Laid-Open No. 3-61507 (Patent Document 1), the strand cut method is a solution obtained by dissolving an EVOH resin (or a composition thereof) in an appropriate solvent. A rod-like strand obtained by extruding into a coagulating liquid from a metal plate having a hole of about 5 mm or extruding a heat-melted resin into a die and solidifying by cooling is cut into a certain size using a cutter. To produce EVOH resin pellets.

Further, as a method for solving the manufacturing problems of the strand cut method (it is difficult to cut a large amount of resin in a short time with high dimensional accuracy), for example, disclosed in JP-A-2001-96530 (Patent Document 2) It has been proposed to cut a water-containing and molten EVOH resin immediately after being discharged from an extruder (hot cut method). This hot cut method is an aerial cut type cutting in which the water-containing molten EVOH resin discharged from the discharge port of the twin-screw extruder is extruded by rotating the rotary blade immediately after the extrusion; cooling the EVOH resin from the extruder There is an underwater cutting method that discharges into a cutter box that satisfies the requirements and cuts in water immediately after discharge.

EVOH resin pellets produced as described above have various shapes and properties depending on the production conditions, and there are variations in the shape of the pellets.
When the EVOH resin pellets are subjected to melt molding, the accuracy of the shape, thickness, etc. of the molded product is affected by the shape and properties of the EVOH resin pellets. In order to improve the dimensional accuracy of the EVOH resin molded product, The properties and shape of the EVOH resin pellet are also important.

Japanese Patent Laid-Open No. 2000-264972 is an invention made by paying attention to the fact that the properties of EVOH resin pellets affect the torque fluctuation, discharge quantity fluctuation, and film thickness fluctuation as a molded product during melt extrusion molding. (Patent Document 3) proposes that the angle of repose represented by the horizontal surface and the height of the mountain of the pellet group obtained by dropping the pellet group and depositing it in a conical shape is in the range of 30 to 45 °. is doing.

In the Example of patent document 3, the relationship between the angle of repose of the cylindrical EVOH resin pellet manufactured by the strand cut method and the torque fluctuation, the discharge amount fluctuation, and the film thickness change when subjected to melt molding is disclosed. .
Specifically, an EVOH resin solution having an ethylene unit content of 35 mol% (Examples 1 and 4), 42 mol% (Examples 2 and 5), and 30 mol% (Example 3) is a cylindrical nozzle. After extruding into a strand shape and making contact for 60 to 120 seconds in a coagulation bath, the obtained strand was cut and dried, and cylindrical pellets obtained by using pellets having an angle of repose of 33 to 38 ° were used. The molding material was small in torque fluctuation, discharge quantity fluctuation, and film thickness change, whereas cylindrical pellets having an ethylene unit content of 35 mol% and an angle of repose of 46 ° with a contact time in the coagulation bath of 10 minutes ( Comparative Example 1) EVOH resin pellets (Comparative Example 2) having an ethylene unit content of 35 mol% and an angle of repose of 28 ° with a lubricant adhesion amount of 1200 ppm had large torque fluctuations, discharge amount fluctuations, and film thickness fluctuations. It has been shown that .

Japanese Patent Laid-Open No. 3-61507 JP 2001-96530 A JP 2000-264972 A

In the manufacturing method of Patent Document 2, it is disclosed that a large amount of resin can be efficiently cut with high dimensional accuracy, and pellets with high dimensional uniformity can be efficiently manufactured. No evaluation was made when it was subjected to melt molding as a material.

On the other hand, Patent Document 3 measures and evaluates torque fluctuation, discharge amount fluctuation, and film thickness fluctuation of an obtained film when EVOH resin pellets as a molding material are subjected to melt molding. However, in recent years, when pellets are introduced into a melt extruder, the flow of the molten resin in the melt plasticizing section has caused problems such as the vibration of the screw and the generation of sound due to torque fluctuations during resin extrusion. Such a problem has not been measured and evaluated in Patent Document 3.
In a state where abnormal noise is generated in the melt plasticizing part of the melt extruder, a burden is applied to the screw, and in a severe case, there is a possibility of causing wear of the screw and mixing of wear powder into the molten resin.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide EVOH resin pellets excellent in feedability as a melt-molding material.

The inventor of the present invention has focused on the production method and shape of EVOH resin pellets, and variously studied the relationship of feed properties in the melt extruder, and has reached the present invention.
That is, the molding material using the saponified ethylene-vinyl ester copolymer of the present invention is a molding material comprising a group of ethylene-vinyl ester copolymer saponified pellets,
The pellet group includes a first saponified ethylene-vinyl ester copolymer saponified pellet having a substantially circular or elliptical cross section, and a second saponified ethylene-vinyl ester copolymer saponified pellet having a cylindrical shape, and The mixing weight ratio (A1 / A2) of the first ethylene-vinyl ester copolymer saponified pellet (A1) and the second ethylene-vinyl ester copolymer saponified pellet (A2) was 99 / 1-20 / 80.

The first ethylene-vinyl ester copolymer saponified product pellet has a substantially circular or elliptical cross section having a major axis of 3.0 to 6.0 mm and a minor axis of 2.5 to 6.0 mm. The saponified ethylene-vinyl ester copolymer pellets preferably have a bottom circle with a diameter of 1.5 to 4.0 mm and a height of 1.5 to 4.0 mm.

The angle of repose of the substantially conical pellet group obtained by allowing the pellet group to flow down from a funnel having a foot diameter (a) of 8 mm into a circular container having a diameter (D) of 9.5 cm is preferably less than 37 °.
In addition, the ethylene content of the first ethylene-vinyl ester copolymer saponified pellet is 20 to 60 mol%, and the ethylene content of the second ethylene-vinyl ester copolymer saponified pellet is It is preferably 20 to 60 mol%.

In this specification, as shown in FIG. 1, the angle of repose refers to an angle α formed by a bus line of a cone-shaped mountain of a pellet group formed by dropping an EVOH resin pellet onto a plane from above and a horizontal plane. Say.
Specifically, as shown in FIG. 2, a glass container (inside dimension: diameter (D) 9.5 cm, height 2 cm) placed horizontally is set to a foot diameter (a ) The EVOH resin pellet 3 is allowed to fall freely through the 8 mm glass funnel 2 until it overflows from the container 1, and the height of the mountain with the horizontal surface on the top surface of the container of the resulting conical EVOH resin pellet group 10 as the base (H) And the angle of repose (°) = tan ⁻¹ (H / 4.75)

In addition, content of the ethylene unit in this specification is a value measured according to ISO14663, for example.
The saponification degree of the vinyl ester component in the present specification is a value measured according to, for example, JIS K6726 (however, EVOH resin is a solution uniformly dissolved in water / methanol solvent).

The molding material of the present invention is excellent in feedability. Therefore, the burden on the melt extrusion molding machine can be reduced.

It is a figure for demonstrating a repose angle. It is a figure for demonstrating the measuring method of a repose angle. It is the photograph which imaged the external appearance of the EVOH resin pellet (A1) group produced in the Example. It is a photograph of the section containing the long axis of pellet A1 produced in the example. It is the photograph of the cross section which cut | disconnected the pellet A1 produced in the Example so that it might orthogonally cross a long axis. It is the photograph which imaged the external appearance of the column-shaped EVOH resin pellet (A2) group produced in the Example. It is the photograph of the cross section cut | disconnected along the height direction of cylindrical pellet A2 produced in the Example. It is the photograph of the cross section which cut | disconnected the cylindrical pellet A2 produced in the Example in parallel with the bottom face.

Hereinafter, the configuration of the present invention will be described in detail, but these show examples of desirable embodiments and are not limited to these contents.

The molding material of the present invention comprises an ethylene-vinyl ester copolymer saponified product (EVOH resin) pellet group, and the pellet group includes a first EVOH resin pellet having a substantially circular or elliptical cross section and a cylindrical shape. A second EVOH resin pellet is included.

First, the EVOH resin that is a constituent material of the pellet group will be described.
<EVOH resin>
The ethylene-vinyl ester copolymer saponified product (EVOH resin) used as the molding material of the present invention is an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and a vinyl ester monomer and then saponifying. It is a saponified coal and is a water-insoluble thermoplastic resin.
Generally, vinyl acetate is generally used as the vinyl ester monomer from the economical aspect. The polymerization method may be any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization, or bulk polymerization. Generally, solution polymerization using methanol as a solvent is used. Moreover, any of a continuous type and a batch type may be sufficient.
As a method for introducing ethylene into the copolymer, ordinary ethylene pressure polymerization may be carried out. The content of ethylene units can be controlled by the pressure of ethylene, and is usually selected from the range of 25 to 80 kg / cm ^{2 according} to the intended ethylene content.

Saponification of the obtained ethylene-vinyl ester copolymer can also be performed by a known method. Such saponification can be performed using an alkali catalyst or an acid catalyst in a state where the copolymer obtained above is dissolved in an alcohol or a hydrous alcohol.
The EVOH resin synthesized as described above mainly contains ethylene units and vinyl alcohol structural units, and contains a slight amount of vinyl ester structural units remaining without being saponified.

The EVOH resin used as the material for the EVOH resin pellets may further contain structural units derived from the comonomer shown below. The comonomer includes α-olefins such as propylene, isobutene, α-octene, α-dodecene, α-octadecene, 3-buten-1-ol, 4-penten-1-ol, 3-butene-1, 2-diol Hydroxyl group-containing α-olefins such as hydroxy group-containing α-olefin derivatives, esterified products, acylated products, etc., unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides, anhydrides, It is a comonomer such as saturated sulfonic acid or a salt thereof, a vinyl silane compound, vinyl chloride, or styrene.

Furthermore, “post-modified” EVOH-based resins such as urethanization, acetalization, cyanoethylation, oxyalkylenation and the like may be used as the EVOH resin.
Among the above modified products, EVOH resins in which primary hydroxyl groups have been introduced into the side chains by copolymerization are preferred in that secondary moldability such as stretching and vacuum / pressure forming is improved. -EVOH resins having a diol structure in the side chain are preferred.

The ethylene unit content (ethylene unit content) of the EVOH resin constituting the EVOH resin pellet group used for the molding material is 20 to 60 mol%, preferably 25 to 50 mol%, more preferably 29 to 48 mol%. is there. If the ethylene unit content is too low, the resulting molded article, in particular, the stretched film tends to have poor gas barrier properties and appearance, and conversely if too high, the stretched film tends to have poor gas barrier properties. .

The saponification degree of the vinyl ester component in the EVOH resin used for the molding material is usually 90 mol% or more, preferably 93 to 99.99 mol%, particularly preferably 98 to 99.99 mol%. When the degree of saponification is too low, the stretched film tends to deteriorate gas barrier properties, moisture resistance, etc., which is not preferable.

The melt flow rate (MFR) (210 ° C., load 2160 g) of the EVOH resin constituting the EVOH resin pellet group used for the molding material is usually 1 to 100 g / 10 minutes, preferably 2 to 50 g / 10 minutes, particularly preferably. Is 3 to 30 g / 10 min. If the MFR is too large, the mechanical strength of the molded product tends to deteriorate, and if it is too small, the extrusion processability during molding tends to deteriorate.

The conditions for copolymerization for synthesizing the EVOH resin as described above are not particularly limited, but usually the following conditions are preferably used.
Examples of the solvent used for such copolymerization include usually lower alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone and methyl ethyl ketone, and methanol is preferably used industrially.
The amount of the solvent used may be appropriately selected in consideration of the chain transfer constant of the solvent in accordance with the degree of polymerization of the target copolymer. For example, when the solvent is methanol, S (solvent) / M ( Monomer) = 0.01 to 10 (weight ratio), preferably 0.05 to 7 (weight ratio).

Examples of the polymerization catalyst used in the copolymerization include known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, lauryl peroxide, t-butylperoxyneodecanoate, and t-butyl. Peroxypivalate, α, α'bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl- Peroxyesters such as 1-methylethylperoxyneodecanoate, t-hexylperoxyneodecanoate, t-hexylperoxypivalate, di-n-propylperoxydicarbonate, di-iso-propyl Peroxydicarbonate], di-sec-butylperoxydicarbonate Bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, dimethoxybutylperoxydicarbonate, di (3-methyl Low temperature active radical polymerization of peroxydicarbonates such as -3-methoxybutylperoxy) dicarbonate, diacyl peroxides such as 3,3,5-trimethylhexanoyl peroxide, diisobutyryl peroxide, lauroyl peroxide A catalyst etc. are mentioned.
The amount of the polymerization catalyst used varies depending on the type of catalyst and cannot be determined unconditionally, but is arbitrarily selected according to the polymerization rate. For example, when azobisisobutyronitrile or acetyl peroxide is used, it is preferably 10 to 2000 ppm, particularly preferably 50 to 1000 ppm based on the vinyl ester monomer.

It is preferable that a hydroxylactone compound or a hydroxycarboxylic acid coexist with the catalyst. Coloring of the pellet can be suppressed. The hydroxylactone compound is not particularly limited as long as it has a lactone ring and a hydroxyl group in the molecule, and examples thereof include L-ascorbic acid, erythorbic acid, glucono delta lactone, and the like. L-ascorbic acid and erythorbic acid are used, and examples of the hydroxycarboxylic acid include glycolic acid, lactic acid, glyceric acid, malic acid, tartaric acid, citric acid, salicylic acid, etc., preferably citric acid is used. It is done.

The amount of the hydroxylactone compound or hydroxycarboxylic acid used is 0.0001 to 0.1 parts by weight, more preferably 0.0005 to 100 parts by weight based on 100 parts by weight of the vinyl ester monomer in both batch and continuous systems. 0.05 part by weight, particularly 0.001 to 0.03 part by weight is preferable. If the amount used is too small, the effect of coexistence may not be sufficiently obtained. As a result of inhibiting polymerization, it is not preferable. There are no particular limitations on the preparation of such compounds in the polymerization system, but usually aliphatic esters containing lower aliphatic alcohols (methanol, ethanol, propanol, tert-butanol, etc.) and vinyl ester monomers (methyl acetate, ethyl acetate). Etc.), a solvent such as water, or a mixed solvent thereof, and charged into the polymerization reaction system.

The copolymerization reaction cannot be generally specified depending on the solvent and pressure to be used, but is usually carried out below the boiling point of the solvent, usually 40 to 80 ° C., preferably 55 to 80 ° C. If the temperature is too low, a long time is required for the polymerization, and if the polymerization time is to be shortened, a large amount of catalyst is required. On the other hand, if the temperature is too high, the polymerization control becomes difficult.

The polymerization time is preferably 4 to 10 hours (more preferably 6 to 9 hours) in the case of a batch system. If the polymerization time is too short, the polymerization temperature must be increased or the amount of catalyst must be set large. Conversely, if the polymerization time is too long, it is not preferable from the viewpoint of productivity. In the case of a continuous type, the average residence time in the polymerization can is preferably 2 to 8 hours (more preferably 2 to 6 hours). If the residence time is too short, the polymerization temperature must be increased or the amount of catalyst must be set large. Conversely, if the polymerization time is too long, there is a problem in terms of productivity, which is not preferable.

The polymerization rate (vinyl ester monomer) is set as high as possible within the range where polymerization can be controlled from the viewpoint of productivity, and is preferably 20 to 90%. If the polymerization rate is too low, there are problems such as productivity and the presence of a large amount of unpolymerized vinyl acetate monomer. Conversely, if the polymerization rate is too high, polymerization control becomes difficult, which is not preferable.

After polymerization for a predetermined time, after reaching a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation, and then unreacted vinyl ester is driven out.
As a method for removing unreacted vinyl ester from the ethylene-vinyl ester copolymer from which ethylene has been removed by evaporation, for example, the copolymer solution is continuously added at a constant rate from the top of a column packed with Raschig ring. The mixed vapor of methanol and other organic solvent and unreacted vinyl ester was distilled from the top of the tower while blowing an organic solvent vapor such as methanol from the bottom of the tower, and the unreacted vinyl ester was removed from the bottom of the tower. A method of taking out the polymer solution is employed.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl ester has been removed to saponify the vinyl ester component in the copolymer.
The saponification is performed using an alkali catalyst or an acid catalyst in a state where the copolymer obtained above is dissolved in an alcohol or a hydrous alcohol. Examples of the alcohol include methanol, ethanol, propanol, tert-butanol and the like, and methanol is particularly preferably used. The concentration of the copolymer in the alcohol is appropriately selected depending on the viscosity of the system, but is usually selected from the range of 10 to 60% by weight. Catalysts used for saponification include alkali catalysts such as alkali metal hydroxides and alcoholates such as sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate and lithium methylate; sulfuric acid, Examples include acid catalysts such as hydrochloric acid, nitric acid, metasulfonic acid, zeolite, and cation exchange resin.

The amount of the saponification catalyst used is appropriately selected depending on the saponification method, the target degree of saponification, etc. When using an alkali catalyst, it is usually based on the total amount of monomers such as vinyl ester monomers. 0.001 to 0.1 equivalent, preferably 0.005 to 0.05 equivalent is appropriate. With respect to such a saponification method, batch saponification, continuous saponification on a belt, and continuous saponification of a tower type are possible depending on the target degree of saponification, etc. For example, column saponification under constant pressure is preferably used because the crystallization reaction is highly efficient and easy to proceed.
Further, the pressure during saponification cannot be generally stated depending on the ethylene unit content of the target EVOH resin, but is selected from the range of 2 to 7 kg / cm ² , and the saponification temperature is 80 to 150 ° C., preferably 100 to 100 ° C. The saponification time is selected from 0.5 to 3 hours. In addition, it is preferable to neutralize EVOH resin after reaction as needed.

As the EVOH resin used as the pellet raw material, the EVOH resin synthesized as described above is generally added to the EVOH resin within a range that does not impair the effects of the present invention, for example, a heat stabilizer, an antioxidant, a charging agent. Inhibitors, colorants, ultraviolet absorbers, plasticizers, light stabilizers, surfactants, antibacterial agents, desiccants, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, antifogging agents An EVOH resin composition containing an additive for biodegradation, a silane coupling agent, an oxygen absorbent and the like may also be used.

<Manufacture of pellets>
The molding material of the present invention is a group of pellets composed of the EVOH resin as described above, (1) a first EVOH resin pellet (A1) having a substantially circular or elliptical cross section, and (2) a columnar EVOH. Contains a mixture of resin pellets (A2).

(1) First EVOH resin pellet (pellet A1)
The first EVOH resin pellet is a pellet having a substantially circular or oval cross section. The cross section is a cross section of the pellet that is not particularly limited, and means that an arbitrary cut cross section is substantially circular or elliptical, that is, has no corners, and has a rounded shape as a whole. Such pellets are usually obtained by melt extrusion and cutting the EVOH resin in a molten state. When EVOH resin is melt-extruded and cut with a cutter before it is cooled and solidified, the edge part produced by cutting hangs down while it is cooled and solidified, and it acts to become spherical due to surface tension. , A pellet composed entirely of a curved surface is obtained. Specifically, although it depends on the shape at the time of melt extrusion (usually a quadratic prism, a cylinder), in addition to a true sphere, it has a shape such as a sphere having a substantially circular or substantially elliptical cross section, a disk shape, or a camel ball shape. .

The shape and size of the pellet A1 are not particularly limited, but the maximum major axis (m) at which the maximum cross-sectional area can be obtained is usually 3 to 6 mm, preferably 3.5 to 5.5 mm, and particularly preferably 4.3 to 5 The maximum minor axis (n) is usually 2.5 to 6 mm, preferably 3 to 5.5 mm, particularly preferably 3.5 to 5.2 mm. When the pellet size is too large, the feed property is lowered, and when the pellet size is too small, it becomes a powder and the handleability is lowered.

The ratio (m / n) of the maximum major axis (m) to the maximum minor axis (n) of the obtained cross section is usually 1 to 2, preferably 1 to 1.8, particularly preferably 1 to 1.5. . When the ratio (major axis / minor axis) is too large, the pellet shape approaches a needle shape, so that the feed property at the time of melt extrusion molding tends to deteriorate. When the ratio of the major axis (m) to the minor axis (n) (m / n) = 1, it means a true sphere.

As the EVOH resin raw material to be charged into the melt extruder for the production of pellet A1, (1-1) the EVOH resin solution or slurry obtained by saponification in the above-mentioned EVOH resin synthesis method is used as it is, or the solution Alternatively, the EVOH resin water-containing composition after appropriately adjusting the water content of the slurry, or (1-2) EVOH resin pellets (dry EVOH resin pellets) obtained by the strand cut method, and the molten EVOH resin Can be used.

(1-1) When the EVOH resin hydrous composition is used as a raw material When the EVOH resin hydrous composition is used as a raw material to be charged into a melt extruder, 0 to 10 parts by weight of alcohol and water are added to 100 parts by weight of the EVOH resin. An EVOH resin water-containing composition containing 10 to 500 parts by weight is preferred.

When the EVOH resin water-containing composition having a high alcohol content is used, it is not possible to prevent the alcohol from being volatilized in a subsequent process, and it becomes difficult to maintain the work environment or the surrounding environment. Further, when the temperature of the pellet washing water is increased for alcohol removal, the pellets are easily stuck together, and conversely, washing at a low temperature increases the washing time and causes a reduction in production efficiency.
On the other hand, when an EVOH resin water-containing composition having a high water content is used, when cutting in a molten state, the pellets after cutting tend to be fused to each other or the pellet shape tends to be inhomogeneous. If the water content is too small, the fluidity of the EVOH resin water-containing composition tends to be insufficient, and the productivity of pellets tends to decrease.

The method for adjusting the moisture content of the EVOH resin hydrous composition for pellet production is not particularly limited, but in order to increase the moisture content, a method of spraying water on the resin, a method of immersing the resin in water, The method of making it contact can be adopted. In order to reduce the water content, it may be dried as appropriate, and for example, it can be dried using a fluid hot air dryer or a stationary hot air dryer. It is preferable to use a fluid hot air dryer from the viewpoint of reducing dry spots. Furthermore, it is preferable that the drying temperature is 120 ° C. or less from the viewpoint of suppressing thermal degradation.

The EVOH resin solution after saponification is usually obtained as a solution containing a large amount of alcohol. By bringing the EVOH resin solution after saponification into contact with water vapor, an EVOH water-containing composition having a low alcohol content is derived from the container. And can be used as a raw material for pellet production.

When the EVOH resin hydrous composition is charged as a pellet raw material into a melt extruder, the temperature of the EVOH resin hydrous composition in the extruder is preferably 70 to 170 ° C, more preferably 80 ° C or higher, and still more preferably 90 ° C or higher. At 170 ° C. or lower. When the temperature of the EVOH resin hydrous composition is less than 70 ° C, the EVOH resin may not be completely melted, and when it exceeds 170 ° C, the EVOH may be susceptible to thermal degradation. In the present specification, the temperature of the resin composition refers to a temperature detected in the vicinity of the discharge port at the tip of the extruder by a temperature sensor installed in the extruder cylinder.

The extruder to be used is not particularly limited, but from the viewpoint of easy handling of the pellets, the diameter (diameter) of the nozzle is usually 1 to 10 mm, preferably 2 to 5 mm.
The number of cutter blades is usually 2 to 24, preferably 3 to 16.
The cutter blade is usually preferably attached so as to be in contact with the discharge port of the die of the extruder. Therefore, the distance between the die and the cutter is 0 mm, but even if there is a distance of about 0.01 to 0.2 mm. Good.
The rotation speed of the cutter blade is usually 500 to 2000 rpm, preferably 1000 to 1500 rpm.
The shape of the pellet can be adjusted by appropriately adjusting the nozzle diameter, the number of cutter blades, the number of rotations of the cutter blade, and the like.

The molten EVOH resin hydrous composition extruded from a die is cut before being cooled and solidified (hot cut method). The hot cut method may be cut in the atmosphere (air hot cut method), extruded into a cutter installation container filled with cooling water, and cut in cooling water (under water cut method). The underwater cutting method can be performed using, for example, an underwater pelletizing apparatus.

The temperature of the cooling water in the underwater cutting method is such a temperature that the EVOH resin extruded in the molten state does not instantly solidify (solidify). When the cooling water contacts with the cooling water before cutting, the temperature of the cooling water is 30. It is preferably set to ˜90 ° C., more preferably 40 to 80 ° C.
The cooling water is not limited to water. Water / alcohol mixtures; aromatic hydrocarbons such as benzene; ketones such as acetone and methyl ethyl ketone; ethers such as dipropyl ether; organic esters such as methyl acetate, ethyl acetate, and methyl propionate it can. Of these, water or a water / alcohol mixed solution is used because it is easy to handle. In the water / alcohol mixed solution, the water / alcohol (weight ratio) is usually 90/10 to 99/1. In addition, as said alcohol, alcohol, such as methanol, ethanol, propanol, can be used, and methanol is used preferably industrially.

(1-2) When using dry EVOH resin pellets as a raw material When using dry EVOH resin pellets as a raw material for EVOH resin pellets (A1), the dry EVOH resin pellets are put into an extrusion kneader and melt-extruded.
The size and shape of the dry EVOH resin pellet used as a raw material are not particularly limited.
The temperature of the EVOH resin in the extrusion kneader needs to be set higher than in the case of the EVOH resin water-containing composition. Specifically, it is usually 150 to 300 ° C, preferably 200 to 285 ° C, and particularly preferably 240 to 270 ° C. When the set temperature is less than 150 ° C., the EVOH resin pellets tend not to melt completely. Conversely, when the EVOH resin temperature exceeds 300 ° C., the EVOH resin tends to be susceptible to thermal degradation. The resin temperature refers to the temperature detected in the vicinity of the discharge port at the tip of the extruder by a temperature sensor installed in the extruder cylinder.

The extruder to be used is not particularly limited, but from the viewpoint of easy handling of pellets, the nozzle diameter (diameter) is usually 1.0 to 5.0 mm, preferably 2.0 to 3.5 mmφ. .
The cutter blade is usually preferably attached so as to be in contact with the discharge port of the die of the extruder. Therefore, the distance between the die and the cutter is 0 mm, but even if there is a distance of about 0.01 to 0.2 mm. Good.
The number of cutter blades is usually 2 to 24, preferably 3 to 16.
The rotation speed of the cutter blade is usually 1000 to 2000 rpm, preferably 1250 to 1750 rpm.
The shape of the pellet can be adjusted by appropriately adjusting the nozzle diameter, the number of cutter blades, the number of rotations of the cutter blade, and the like.

The melt-extruded EVOH resin is cut before being cooled and solidified (hot cut method). As for the hot cut method, as in the case of using the EVOH resin water-containing composition as a raw material, either an air hot cut method or an underwater hot cut method may be adopted. Similarly, it is usually 30 to 90 ° C, preferably 40 to 80 ° C. The cooling water is not limited to water, and the solutions listed when the EVOH resin water-containing composition is used as a raw material may be used as the cooling water.

(2) Cylindrical EVOH resin pellet (pellet A2)
The second EVOH resin pellet (pellet A2) is a columnar EVOH resin pellet which is a so-called circle or ellipse whose corner is the corner between the bottom and side, and is cooled and solidified rod-shaped EVOH resin. It refers to a pellet whose corners are cut as a result of cutting a strand every predetermined length.
The cylindrical bottom corresponds to the cross-sectional shape of the strand, and includes a case where the cross-section is circular or elliptical depending on the shape of the strand.

The diameter (x) of the bottom surface and the top surface of the pellet A2 is usually 1.5 to 4.0 mm, preferably 1.8 to 3.7 mm, more preferably 2.0 to 3.5 mm. The length (y) of the corresponding cylindrical pellet is usually 1.5 to 4.0 mm, preferably 1.8 to 3.7 mm, more preferably 2.0 to 3.5 mm. When the diameter or length of the bottom surface is too small or too large, the feed property at the time of melt extrusion molding tends to deteriorate.

The ratio (x / y) of the diameter (x) to the length (y) of the bottom surface and the top surface of the cylindrical EVOH resin pellet (pellet A2) is usually 0.5 to 2.0, preferably 0.7 to 1.5, more preferably 0.9 to 1.2. When the ratio of the diameter and length of the bottom surface and the top surface is too small or too large, the feed property at the time of melt extrusion molding tends to deteriorate.

Such cylindrical pellets are usually made into pellets by cutting the strands obtained by extruding the EVOH resin solution through a nozzle into the coagulation liquid, and then washing with water. Accordingly, after contact with an aqueous solution of the additive, it is obtained by drying treatment.

The EVOH resin solution used as the raw material for the cylindrical pellet may be any solution obtained by dissolving the EVOH resin in a suitable solvent.
The EVOH resin solution used as a raw material is prepared by dissolving i) EVOH resin powder or pellets in a solvent or a solvent / water mixed solvent so as to have a predetermined concentration, or ii) KenOH obtained in the production of EVOH resin. The solvent, water or a mixed solvent thereof is added to the EVOH resin solution after the chemical treatment to adjust the resin concentration and solution viscosity, or iii) Precipitation or precipitation / water-washed EVOH resin pellets in EVOH production Can be prepared by dissolving in a solvent or a solvent / water mixed solvent to have a predetermined concentration and liquid composition. Of these, the method ii) can be suitably employed in production.

The solvent for dissolving the EVOH resin may be dissolved in a solvent capable of dissolving the EVOH resin, and the solvent and method thereof are not limited, but examples of the solvent include methanol, ethanol, propanol, phenol, dimethyl sulfoxide. Examples thereof include solvents such as side (DMSO), dimethylformamide (DMF), hexafluoroisopropanol (HFIP), and aqueous solutions (mixed solvents) containing these solvents.

When an EVOH resin aqueous solution is used as the EVOH resin solution, the water / solvent mixing weight ratio is preferably in the range of 80/20 to 5/95, and the concentration of the EVOH resin contained in the EVOH resin solution is as follows. Usually, it is 10 to 60% by weight, preferably 15 to 50% by weight. If the concentration is too low, solidification in the coagulation liquid becomes difficult. On the other hand, if the concentration is too high, the porosity of the resulting pellets is lowered, which adversely affects the thermal stability during molding.

The EVOH resin solution is extruded as a strand into the coagulation liquid by a nozzle having an arbitrary shape. The shape of the nozzle is not particularly limited, but a cylindrical shape is preferable, the length is preferably 1 to 100 cm, more preferably 3 to 30 cm, and the inner diameter is preferably 0.1 to 10 cm, further 0.2 to 5 0.0 cm.
A die having a plurality of holes serving as nozzles may be used. In such a case, several to several hundred strands are extruded depending on the number of holes.

The temperature at the time of extruding the EVOH resin solution into the coagulation liquid is usually 10 to 100 ° C., preferably 20 to 60 ° C. When the temperature at the time of extrusion of such an EVOH resin solution is too low, it tends to precipitate and solidify in the extruder, and conversely, when it is too high, the solidification property tends to decrease.

As the coagulation liquid, it is necessary to use a liquid in which EVOH resin does not dissolve. Specifically, water or water / alcohol mixed solvent, aromatic hydrocarbons such as benzene, ketones such as acetone and methyl ethyl ketone, dipropyl ether And ethers such as methyl acetate, ethyl acetate, and organic acid esters such as methyl propionate can be used. From the viewpoint of handleability, water or a water / alcohol mixed solvent (usually the weight ratio of water / alcohol is 5/95 to 99/1) is preferably used. As the alcohol, alcohols such as methanol, ethanol and propanol can be used, and methanol is preferably used industrially.

The temperature of the coagulation liquid when the EVOH resin solution is brought into contact with the coagulation liquid is preferably −10 to 40 ° C., and more preferably 0 to 20 ° C. Since the coagulation liquid also has a role of cooling and solidifying to obtain a strand, it is preferable that the coagulation liquid be at a low temperature from the viewpoint of shortening the coagulation time.
The residence time of the EVOH resin in the coagulation liquid is usually 10 to 400 seconds, preferably 30 to 200 seconds, and particularly preferably 50 to 150 seconds. If the residence time is too short, the coagulation property tends to decrease, and conversely if too long, the productivity tends to decrease.

The strand-like EVOH resin solution extruded into the coagulation liquid is further cooled and solidified with a cooling liquid, and then cut with a strand cutter such as a fixed blade or a rotary blade at predetermined intervals. Thereby, a cylindrical pellet having a height corresponding to the cut length is obtained.

(3) Post-treatment The pellets obtained as described above (pellet having a substantially circular or elliptical cross section, columnar pellet) are preferably further washed with water. Depending on the raw materials used, if there is a risk of containing an alkali metal salt, which is a catalyst residue used during saponification, wash with water from the viewpoint of preventing coloring of the final molded product. Is preferred.

Washing with water is performed in a water bath at 10-60 ° C. For example, 200 to 1000 parts by weight (preferably 300 to 600 parts by weight) of water with 100 parts by weight of EVOH resin pellets at 20 to 50 ° C. (preferably 25 to 35 ° C.) for 0.5 to 5 hours, It is preferable to carry out 1 to 5 times (preferably once). By such washing with water, the content of alcohol, acetic acid and sodium acetate having 5 or less carbon atoms in the EVOH resin is adjusted, and oligomers and impurities can also be removed.

By washing with water, 0.0001 to 1 part by weight of alcohol having 5 or less carbon atoms, 0.01 to 1 part by weight of acetic acid, and 0.01 to 1 part by weight of sodium acetate with respect to 100 parts by weight of EVOH resin pellets. It is preferable to adjust the part.

After washing with water, if necessary, the EVOH resin pellets are brought into contact with an aqueous solution of the additive.
Examples of the additive include organic acids such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, and behenic acid, or alkali metal salts thereof (sodium, potassium, etc.), alkaline earth metal salts (calcium, Magnesium), zinc salts and the like; or inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, boric acid, or alkali metal salts thereof (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium) Etc.), and heat stabilizers such as salts such as zinc salts.
Of these, it is particularly preferable to add boron compounds, acetates and phosphates including acetic acid, boric acid and salts thereof.
By bringing the additive into contact with an aqueous solution of the additive, the additive can be contained in the EVOH resin pellet, and various physical properties such as thermal stability during melt molding can be improved.
As a method of bringing the additive into contact with an aqueous solution of additive, an aqueous solution of additive of 3% or less (preferably 0.3 to 1.5%) is added in an amount of 200 to 1000 parts by weight (preferably 100 parts by weight of EVOH resin pellets). 300 to 600 parts by weight) and carried out at 10 to 80 ° C. (preferably 20 to 60 ° C., particularly preferably 30 to 40 ° C.) for 0.5 to 5 hours and 1 to 3 times (preferably once) Is done.

By contact with an aqueous solution of the additive, 0.001 to 1 part by weight of acetic acid and boron compound are usually converted into boron based on 100 parts by weight of EVOH resin pellet (analyzed by ICP emission spectrometry after ashing). ) 0.001 to 1 part by weight, acetate or phosphate (including hydrogen phosphate) converted to metal (after ashing and analyzed by ICP emission spectrometry) 0.0005 to 0.1 parts by weight It is preferable to adjust to the part.

As described above, the EVOH resin pellets in which the concentration of each component is adjusted are dried. The moisture content of the EVOH resin pellets after drying is usually 1% by weight or less, particularly 0.5% by weight or less.
The drying method is not particularly limited, and examples thereof include a method using a centrifugal dehydrator, a method of draining water during air transportation, a stationary drying method, a fluidized drying method, and the like. A stepwise drying process may be performed.

In the EVOH resin pellets thus obtained, if necessary, a compounding agent generally incorporated into the EVOH resin within a range not inhibiting the effects of the present invention, such as an antioxidant, an antistatic agent, a colorant, an ultraviolet ray Absorber, lubricant, plasticizer, light stabilizer, surfactant, antibacterial agent, desiccant, antiblocking agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, antifogging agent, biodegradation additive An agent, a silane coupling agent, an oxygen absorbent and the like may be contained.

<Preparation of molding material>
The molding material of the present invention is a mixture of EVOH resin pellets (A1) and EVOH resin pellets (A2) produced as described above.
The composition of the EVOH resin constituting the pellet A1 and the pellet A2 (ethylene unit content, saponification degree, type of additive, content, etc.) may be the same or different.

The blending ratio (A1 / A2) (weight ratio) of the pellets A1 and A2 is usually 99/1 to 20/80, preferably 97/3 to 55/45, particularly preferably 95/5 to 80 /. 20.
When the ratio of the pellet A1 is too small, the feed property at the time of melt extrusion molding tends to decrease. On the other hand, when the ratio is too large, it is difficult to obtain the mixing effect of the columnar pellets. There is a tendency for the feed property of to decrease.

As a method of mixing the pellet A1 and the pellet A2, for example, a mechanical mixing method, specifically, a mixing device such as a Banbury mixer may be used, or mixing is performed by manually stirring, shaking, or the like. May be.

In addition to the mixture of the EVOH resin pellets A1 and EVOH resin pellets A2, the molding material according to the present invention may further comprise the composition of the EVOH resin (ethylene unit content, saponification degree) as long as the effects of the present invention are not impaired. EVOH resin pellets (third EVOH resin pellets) having different shapes, sizes, etc.), pellet shapes and sizes. In this case, the third EVOH resin pellet may be a so-called cornerless pellet or a cylindrical pellet cut in a molten state. In the EVOH resin pellet group constituting the molding material of the present invention, even if the third EVOH resin pellet is contained, it is a combination of the pellet A1 and the pellet A2, and the mixing weight ratio of the pellet A1 and the pellet A2 (A1 / A2) is preferably 99/1 to 20/80, preferably 97/3 to 55/45, and more preferably 95/5 to 80/20.

The molding material of the present invention is a group of pellets obtained as described above, and the repose angle is preferably less than 37 °, more preferably 30 to 36 °, and particularly preferably 32 to 36 °.
As shown in FIG. 1, the angle of repose is formed by a conical generatrix and a horizontal plane of a conical pellet group 10 formed by dropping an EVOH resin pellet group onto a plane from above using a funnel or the like. Refers to the angle α.
Specifically, as shown in FIG. 2, a glass container (inside dimension: diameter (D) 9.5 cm, height 2 cm) placed horizontally is set to a foot diameter (a ) The EVOH resin pellet 3 is dropped freely through the 8 mm glass funnel 2 until it overflows from the container 1. For the substantially conical EVOH resin pellet group 10 formed by depositing EVOH resin pellets, the distance (cone height: H) from the bottom surface inside the container 1 to the apex is measured, and the arc tangent function shown in the following equation Is calculated as
Angle of repose (°) = tan ^-1 (H / 4.75)

It means that the smaller the angle of repose, the more difficult the pellets are deposited, that is, the pellets are more slippery, and thus the feed property is better. Although the reason is not clear, the molding material of the present invention is a group of pellets having different shapes and sizes, so that it is difficult to deposit densely, in other words, it is assumed that the pellets easily flow without being deposited. To do.

The molding material of the present invention comprising the above-described pellet group is excellent in feedability. In this regard, even when a so-called non-cornered pellet having a substantially circular or elliptical cross section obtained by cutting in a molten state is used, it is fed only when the EVOH resin pellet without the corner is used. I can not satisfy the sex. Furthermore, even if it is a pellet mixture which combined the pellet without a corner | angular and a cylindrical pellet, if the mixture ratio of a cylindrical pellet becomes high too much, feed property will fall.

<Uses of molding materials>
Since the molding material of the present invention having the above-described configuration is excellent in feed property, it is preferably used as a melt molding material for producing an EVOH resin molded product. In particular, it can be suitably used as a material for melt extrusion molding of films, sheets, fibers and the like. As such melt molding methods, extrusion molding methods (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and injection molding methods are mainly employed.

The conditions and types of the molding machine to be used are not particularly limited, but different types of pellets need to be uniformly mixed during melt-kneading extrusion. From this point of view, the melt plasticizing part may be either a screw type or a plunger type, but is preferably a screw type. The extruder may be either a vertical type or a horizontal type, and may be either a single screw type or a twin screw type. Further, L / D (screw length / screw diameter) and compression ratio (C) of the screw are not particularly limited, but usually L / D is 20 to 35, preferably 25 to 30, and usually C is 1.5 to 8 , Preferably within the range of 2-5.
The melt molding temperature is generally selected from the range of 150 to 300 ° C.

Films and sheets can be used as they are for various purposes by molding, but they are usually used as a laminate by laminating with other base materials in order to further increase the strength or impart other functions. The EVOH resin film, sheet or laminate thereof obtained by using the molding material of the present invention is used as a packaging material for food packaging materials, industrial chemical packaging materials, agricultural chemical packaging materials, and the like based on excellent gas barrier properties. Further, the EVOH resin film, sheet or laminate thereof may be further formed into a cup or bottle.

A thermoplastic resin is useful as another substrate used in the laminate. Examples of the thermoplastic resin include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and the like, polypropylene, ethylene-propylene (block and random) copolymers, propylene -Α-olefin (α-olefin having 4 to 20 carbon atoms) copolymers, polyolefins such as polybutene and polypentene, grafted polyolefins obtained by graft-modifying these polyolefins with unsaturated carboxylic acids or esters thereof, ionomers, ethylene -Vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polyester resin, polyamide resin (including copolymer polyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin Fats, polystyrene, vinyl ester resins, polyester elastomers, polyurethane elastomers, halogenated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, aromatic or aliphatic polyketones, and polyalcohols obtained by reducing them. However, from the viewpoint of practicality such as physical properties (particularly strength) of the laminate, polyolefin resins and polyamide resins are preferable, and polyethylene and polypropylene are particularly preferably used.
As the other base material, any base material (paper, metal foil, uniaxial or biaxially stretched plastic film or sheet, woven fabric, non-woven fabric, metallic cotton, wood, etc.) other than the thermoplastic resin may be used. .

These base resins contain an antioxidant, an antistatic agent, a lubricant, a core material, an antiblocking agent, an ultraviolet absorber, a wax and the like as conventionally known within a range not impairing the gist of the present invention. May be.

The lamination method when laminating the resin composition of the present invention with another substrate can be carried out by a known method. For example, a method of melt extrusion laminating another substrate to the film, sheet or the like of the resin composition of the present invention, conversely, a method of melt extrusion laminating the resin to another substrate, the resin and another substrate A method of co-extrusion, a method of dry laminating the resin (layer) and another substrate (layer) using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound, or the like For example, a method of removing the solvent after coating the resin solution on the material.
Among these, the co-extrusion method is preferable from the viewpoint of cost and environment. Even when the molding material of the present invention is used, it can be applied to extrusion molding with other thermoplastic resins. Since the molding material of the present invention is excellent in film moldability, that is, fluctuation in the width of the film to be melt-extruded is suppressed, production of a multilayer structure applied to melt co-extrusion with other thermoplastic resins Can be suitably used.

The shape of the laminate is not particularly limited, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and a modified cross-section extrudate. The layer structure of the laminate is a film when the EVOH resin layer is x (x1, x2,...) And another substrate, for example, the thermoplastic resin layer is y (y1, y2,...). In the case of a sheet or bottle, not only x / y two-layer structure but also y / x / y, x / y / x, x1 / x2 / y, x / y1 / y2, y2 / y1 / x / Arbitrary combinations such as y1 / y2 are possible. In the filament form, x and y can be any combination such as bimetal type, core (x) -sheath (y) type, core (y) -sheath (x) type, or eccentric core-sheath type.

The laminated body can be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. .
The laminate may be used as it is in various shapes, but it is also preferable to perform a stretching treatment in order to further improve the physical properties of the laminate, and for such stretching, uniaxial stretching or biaxial stretching is preferable. Any of them may be used, and stretching as high a magnification as possible is preferable in terms of physical properties, and a stretched film or stretched sheet in which pinholes, cracks, stretching unevenness, delamination, etc. do not occur during stretching can be obtained.

As the stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, or the like, or a deep drawing method, a vacuum forming method, or the like having a high stretching ratio can be employed. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. The stretching temperature is selected from the range of about 80 to 170 ° C, preferably about 100 to 160 ° C.

It is preferable to perform heat setting after the stretching treatment. The heat setting can be performed by a known means, and the stretched film is heat-treated at 80 to 170 ° C., preferably 100 to 160 ° C. for about 2 to 600 seconds while maintaining a tension state.

When the laminated film is used for heat shrink packaging applications such as raw meat, processed meat, cheese, etc., after the raw meat, processed meat, cheese, etc. are packaged using a film that is not heat-set after stretching, The film is preferably heat-shrinked at 70 to 120 ° C. for about 2 to 300 seconds to heat-shrink and tightly wrap.

The film, sheet or container obtained as described above is useful as various packaging materials such as foods, pharmaceuticals, industrial chemicals and agricultural chemicals.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “part” means a weight basis unless otherwise specified.

[Manufacture of molding materials No. 1 to 11]
(1) EVOH resin pellet having a substantially circular or oval cross section (pellet A1)
Cylindrical EVOH resin pellets having a water content of 0.1% (ethylene unit content: 29 mol%, saponification degree: 99.6 mol%, MFR: 4.0 g / 10 min (210 ° C., load 2,160 g) ) As raw materials, melted and kneaded under the following conditions, and when the molten EVOH resin solution is extruded from the discharge port into the cooling water (16 sheets) attached to the discharge port (16 sheets) Cutting with a blade) (underwater cutting method). By drying, a rugby ball-shaped EVOH resin pellet having an elliptical cross section with a maximum major axis of 4.6 mm and a maximum minor axis of 3.5 mm was obtained. The photograph which imaged the external appearance of the said pellet group, the photograph of the cross section cut | disconnected by the surface containing the major axis of rugby ball-shaped pellet A1, the photograph of the cross section of the pellet A1 cut | disconnected orthogonally to the major axis, FIG. , 5 in order.
As shown in FIG. 3, the rugby ball-shaped pellet A1 having a cross section as shown in FIGS. 4 and 5 has no corners even if it exists at any inclination.

-Screw inner diameter: 70mm
・ L / D: 39
・ Screw rotation speed: 300rpm
-Die temperature: 260 ° C
・ Cylinder temperature (highest part): 260 ℃
・ Nozzle diameter: 3.2mmφ
・ Discharge rate: 350kg / h
・ Rotation speed of cutter blade: 1500rpm
・ Cooling water temperature: 60 ℃

(2) Cylindrical EVOH resin pellet (pellet A2)
EVOH resin (ethylene unit content: 29 mol%, saponification degree: 99.6 mol%, MFR: 3.4 g / 10 min (210 ° C., load 2160 g)) in a water / methanol mixed solution (water / methanol = 40 / 60 (weight ratio), EVOH resin concentration 45%) in a coagulation bath (water / methanol = 95/5 mixing weight ratio) maintained at 5 ° C., cylindrical shape with an inner diameter of 0.4 cm and a length of 6.0 cm After being extruded in a strand form from a nozzle of No. 1 and solidified by being retained in a coagulation bath for 100 seconds, cutting was performed using a cutter (strand cutting method). Thereafter, drying was performed to obtain cylindrical EVOH resin pellets having a diameter of 2.5 mm at the bottom and top surfaces and a height of 2.6 mm. FIGS. 6, 7, and 8 show a photograph of the appearance of the pellet group, a photograph of the pellet cross section cut along the height direction of the cylindrical pellet, and a photograph of the pellet cross section cut parallel to the bottom surface in order.

(3) Molding material (mixture of pellets)
The pellets A1 and pellets A2 produced above were blended in the weight ratios shown in Table 1, put into a plastic bag, and mixed by vigorously shaking the bag at 15 ° C. in the atmosphere. 1-9 were produced. As for molding materials No. 10 and 11, pellet A1 and pellet A2 were used as the molding materials, respectively.
The angle of repose of each molding material was measured by the following method, and the feed property was evaluated.

[Measurement of repose angle]
As shown in FIG. 2, a glass funnel having a foot diameter (a) of 8 mm from a height of 10 cm from the upper surface of the container 1 to a horizontally placed glass container (inner dimensions: diameter (D) 9.5 cm, height 2 cm). The EVOH resin pellet 3 is freely dropped through 2 until it overflows from the container 1. For the substantially conical EVOH resin pellet group 10 formed by depositing EVOH resin pellets, the distance (cone height: H) from the bottom surface inside the container 1 to the apex is measured, and the arc tangent function shown in the following equation Calculated as The measurement was performed three times, and the average value was defined as the angle of repose (α).
Angle of repose (°) = tan ^-1 (H / 4.75)

[Production of EVOH resin film and evaluation of feed property]
Using each of the molding materials Nos. 1 to 11 produced above, a film was formed under the following conditions to obtain an EVOH resin film having a thickness of 50 μm.
(Film forming conditions)
・ Screw inner diameter 19mm
・ L / D 25
・ Screw compression ratio 2
・ T die Coat hanger type ・ Die width 150mm
Extrusion temperature (° C.) C1 / C2 / C3 / C4 / C5 (adapter) / C6 (die) = 200/23
0/230/230/230/230

An abnormal noise generated from the extruder during the film formation of the EVOH resin film was confirmed with an ear standing at a position about 50 cm away from the extruder, and the feed property was evaluated.
○: Abnormal noise is hardly heard Δ: Abnormal noise is heard ×: Violent abnormal noise is heard The smaller the abnormal noise is, the better the feed property is.

From Table 1, the molding material (No. 10) consisting only of rugby ball-shaped EVOH resin pellets and the molding material (No. 11) consisting only of columnar EVOH resin pellets tend to have a high angle of repose and feed properties. Was inferior.
Even if the molding material is composed of a mixture of rugby ball-shaped EVOH resin pellets (pellet A1) and cylindrical EVOH resin pellets (pellet A2), if the amount of pellets A2 is too large, the angle of repose will not be reduced and the feed property will be reduced. No improvement was observed (No. 7-9).

When the mixture weight ratio (A1 / A2) was 25/75 or more, the repose angle was 36 ° or less, and the feed property could be satisfied (No. 1 to 6).
In particular, when the pellet A1 is a mixture of the pellet A1 and the pellet A2 and the pellet A1 occupies more than 50% by weight of the pellet group, the angle of repose is 35 ° or less and has excellent feedability.

The molding material of the present invention is extremely useful industrially because it is excellent in feed property at the time of melt extrusion molding.

3 pellets 10 pellets

Claims (4)

1. A molding material comprising a group of saponified ethylene-vinyl ester copolymer saponification products,
   The pellet group includes a first ethylene-vinyl ester copolymer saponified pellet having a substantially circular or elliptical cross section, and a columnar second ethylene-vinyl ester copolymer saponified pellet,
   The mixing weight ratio (A1 / A2) of the first ethylene-vinyl ester copolymer saponified pellet (A1) and the second ethylene-vinyl ester copolymer saponified pellet (A2) is 99. / 1 to 20/80 molding material.
2. The saponified pellet of the first ethylene-vinyl ester copolymer has a substantially circular or elliptical cross section having a major axis of 3.0 to 6.0 mm and a minor axis of 2.5 to 6.0 mm,
   The molding material according to claim 1, wherein the saponified pellet of the second ethylene-vinyl ester copolymer has a bottom circle diameter of 1.5 to 4.0 mm and a height of 1.5 to 4.0 mm.
3. The repose angle of a substantially conical pellet group obtained by allowing the pellet group to flow down from a funnel having a foot diameter (a) of 8 mm into a circular container having a diameter (D) of 9.5 cm is less than 37 °. The molding material as described in 2.
4. The ethylene content of the first ethylene-vinyl ester copolymer saponified pellet is 20 to 60 mol%, and the ethylene content of the second ethylene-vinyl ester copolymer saponified pellet is 20 to 60 mol%. The molding material according to any one of claims 1 to 3, which is 60 mol%.

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